The present invention relates to a keyless tool chuck, and more particularly relates to an improvement in construction of a chuck for firmly holding a tool such as a drill bit or a driver bit of electric work devices without assistance by a chuck key. This invention relates to a chuck for use with rotating equipment such as drills. Such rotating equipment is commonly driven manually or in the case of power drivers, electrically, hydraulicly or pneumatically. More particularly, the present invention relates to a keyless style of chuck which may be tightened or loosened by hand and can alternatively be tightened or loosened by rotation of a key after insertion into a recess formed in the chuck body.
Both hand and powered tool drivers are well known. The general configuration is a rear rotational driver, mechanically coupled to a chuck by threaded engagement or via a tapered sleeve that mates into a corresponding recess in the chuck body. The chuck has any number of circumferentially equally spaced jaws that are advanced concurrently both axially outward and radially inward from a front orifice. It is the advancement of these jaws that grip a tool or bit. The chuck may be used to hold any one of a multitude of tools such as screw or nut drivers and cutting, shaping or grinding bits, although the most common is a twist drill. With such a diverse selection of tool bits, the diameters and configurations of the shanks vary considerably from circular to polygonal in cross section. For this reason the chuck is adjustable over a relatively wide range.
Numerous chucks have been developed and are well known in the art. The most common type is found on the household hand drill. This is perhaps the most simple configuration with three jaws approximately spaced circumferentially 120 degrees apart from each other. Each jaw is housed in an angularly disposed passageway in the chuck body configured so that rotation of the chuck body in one direction with respect to a constrained nut engaging the jaws forces the jaws into gripping relationship with the tool bit. Counter rotation acts to release the gripping relationship. The rotation is commonly accomplished through the use of a key. If sufficient torque can be developed by hand rotation of the chuck, I.E. enough torque to hold the tool bit such that the rotating tool may be used without the disengagement or loosening of the tool bit from the jaws of the chuck, a key is not necessary. This is known as a xe2x80x9ckeylessxe2x80x9d chuck, and the act of securing a tool bit in this manner is known as xe2x80x9ckeylessxe2x80x9d operation. This is a desirable configuration in that bits can be quickly removed or inserted and lost or damaged keys do not hinder the process.
In the current state of the art, key and keyless chucks both have several disadvantages. First if they require a key, it is made of a specific size as all keys are not interchangeable. Keys are easily lost and the engagement teeth can become stripped. Replacement keys can often be hard to find. Second, this type of tightening is slow as it requires insertion and separate tightening at different axial positions around the chuck. If it is a hand tightening chuck it often does not hold the tool bit secure enough for arduous operations, or conversely it holds the tool bit too firm such that hand release of the bit is extremely difficult. The disadvantages of the keyed and keyless chucks are in direct opposition to their respective advantages. It would be desirable to have a hybrid style of chuck that is keyless with a backup keyed operation to remedy all of these drawbacks in the existing chucks. It would be desirable if the keyed operation was accomplished by a standard and commonly available key. Elimination of the multiple keying operations would serve to maintain the ease and speed of tightening the tool bits in the keyed fashion as would less turns of the key to advance and tighten the jaws. It would also be desirable to have a keyless chuck that requires fewer components or has a lower manufacturing cost.
In accordance with the invention, a keyless chuck includes a rotatable hand tightening knob with a planar ring gear on the back surface lying perpendicular to the axis of rotation. A pinion gear is housed in an internal cavity between the chuck body and a tail piece and is in mating engagement with the ring gear such that the pinion gear rotates as the tightening knob is rotated when advancing and closing the jaws. The pinion gear has a recess which is accessible through an orifice in the tail piece and is adapted accept a key device such as an hex key, or a screwdriver that when inserted and rotated, can provide additional torque to open or close the jaws. A second embodiment utilizes a substantially similar configuration but incorporates an idler gear to reverse rotation between the pinion gear and the tightening knob.
In a third embodiment of the keyless chuck, a keyless chuck includes a rotatable hand tightening knob with a pinion gear housed in a void formed in the tightening knob. The tail piece of the chuck has an planar ring gear on the front surface that lies perpendicular to the axis of rotation where the ring gear is in mating engagement with the pinion gear such that the pinion gear rotates as the knob is rotated to advance and close the jaws. The pinion gear has a recess that is accessible through an orifice in the tightening knob and corresponds to a key device such as an hex key, that when inserted and rotated, can provide additional torque to open or close the jaws.
In a fourth embodiment a keyless chuck includes a rotatable hand tightening knob with an planar ring gear formed on its back surface lying perpendicular to the axis of rotation. A tail piece has a planar ring gear on a front surface lying perpendicular to the axis of rotation and positioned such that its teeth oppose the teeth of the planar ring gear of the tightening knob. A pinion gear is housed in an internal cavity of a floating ring that fits between the knob and tail piece such that the pinion gear is matingly engaged with both the tail piece ring gear and the knob ring gear. The floating ring and pinion gear have corresponding recesses to accept a keyed device such as a hex key, that when inserted and rotated, will rotate the knob and tail piece in opposite directions thereby providing additional torque to open or close the jaws and closing the jaws in less turns as in the first and second embodiments.
In the final embodiment a keyless chuck includes a rotatable hand tightening knob with a planar ring gear formed on the back surface lying perpendicular to the axis of rotation. A set of two gears, a first pinion gear and a second idler gear are housed in an internal cavity of the tail piece such that the idler gear is in mating engagement with the ring gear. The idler gear rotates as the knob is rotated to advance and close the jaws. This causes the pinion gear to rotate in the opposite direction of the idler gear. The tail piece and pinion gear have corresponding recesses to accept a keyed device such as an hex key, that when inserted and rotated, can provide additional torque to open or close the jaws. This embodiment changes the direction that the pinion gear is rotated in the preferred embodiment to accomplish the same effect.
Accordingly, it is an object of the present invention to provide an improved keyless chuck with the ability to use a key to gain additional mechanical advantage to tighten or loosen the jaws.
It is a further object of the present invention to provide an improved chuck that uses a standard fastener tool to tighten or loosen the jaws.
It is yet another object of the present invention to provide an improved keyless chuck that eliminates the multiple keying operations common to the chuck industry.
It is still a further object of the present invention to provide an improved keyless chuck capable of an increased tightening torque over conventional chucks.
It is a final object of the present invention to provide an improved chuck that would require a minimum number of key turns to advance and tighten the jaws thus serving to increase the ease and speed of tightening the tool bits in the keyed fashion.
The subject matter of the present invention is particularly pointed out and distinctly claimed in the concluding portion of this specification. However, both the organization and method of operation, together with further advantages and objects thereof, may best be understood by reference to the following description taken in connection with accompanying drawings wherein like reference characters refer to like elements. Other objects, features and aspects of the present invention are discussed in greater detail below.